1. Field of the Invention.
The present invention relates to a sealing plug, in particular a one-piece type rubber plug for a watertight connector through which plug box-shaped terminal fittings can be inserted. The present invention also is directed to a rubber plug for a watertight connector through which plug terminal fittings having stabilizers are suitably insertable. Furthermore the invention relates to a watertight connector having such a sealing plug.
2. Description of the Related Art.
A prior art one-piece waterproof rubber plug is fittable into an opening in the rear surface of a housing. The housing is formed with cavities and insertion holes are formed in positions in the prior art plug that correspond to the respective cavities. A wire with a terminal fitting at its end is inserted into the housing by first inserting the terminal fitting through the insertion hole of the prior art plug. This insertion of the terminal fitting through the insertion hole causes a widening the insertion hole. The terminal fitting eventually passes through the insertion hole and is accommodated in the corresponding cavity of the housing. The insertion hole then is restored elastically to its original smaller shape, and comes into sealing contact with the outer surface of the wire to provide a secure sealing. If the terminal fitting is box-shaped, the inner surface of the insertion hole may be scratched or damaged by the corner of the box and sealability may not be secured.
A known rubber plug that is used for box-shaped terminal fittings is disclosed in European Patent Application Publication No. 0 407 863 and is shown in FIG. 21. This prior art rubber plug is shaped such that the insertion hole 1 is rectangular at an entrance side in conformity with the outer configuration of the terminal fitting 5 and circular at an exit side so that the insertion holes 1 can be held in sealing contact with the outer surface of wire 6. Further, hollow escape portions 4 are formed around the circular holes 2.
Accordingly, when a box-shaped terminal fitting 5 is inserted, an inner portion 3 of the circular hole 2 displaces toward the escape portion 4, and prevents the inner surface of the circular hole 2 from being scratched or damaged.
The inner portion 3 around the circular hole 2 should come into sealing contact with the outer surface of the wire 6. However, the inner portion 3 is thinned in the prior art construction by forming the escape portion 4 around the circular hole 2. This results in an insufficient elastic force, which is not necessarily satisfactory in view of sealability.
Moreover, many prior art terminal fittings have been formed with stabilizers in recent years to stabilize the insertion of these terminal fittings into cavities and to prevent an upside-down insertion. Insertion of such a prior art terminal fitting may cause the stabilizer to scratch or damage the inner surface of the insertion hole or to damage the stabilizer, thereby resulting in insufficient sealability. As a result, the terminal fittings that have stabilizers cannot be used when this prior art one-piece type rubber plug.
The present invention was developed in view of the above problems and an object thereof is to provide a waterproof plug and a watertight connector, which have a high sealability and which are prevented from a scratch or damage caused by portions of terminal fittings.